1. Field of the Invention
The present invention relates to a silver halide photographic light-sensitive material and, more particularly, to a silver halide emulsion with a high photographic sensitivity and a photographic light-sensitive material using the emulsion.
2. Description of the Related Art
Many silver halide emulsions for use in the manufacture of silver halide photographic light-sensitive materials contain silver halide compound crystals of a type consisting of two kinds of crystal faces: a (100) face and a (111) face.
According to the report by A. MIGNOT, E. FRANCOIS AND M. CATINAT, "CRISTAUX DE RBOMURE D' ARGENT PLATS, LIMITES PAR DES FACES (100) ET NON MACLES," Journal of Crystal Growth 123 (1974), pages 207 to 213, tabular silver bromide crystals having square or rectangular major faces and constituted by (100) faces were observed.
U.S. Pat. No. 4,063,951 discloses that tabular grains constituted by (100) crystal faces are formed from mono-disperse seed grains, and, when ripened in the presence of ammonia, these tabular grains are formed to have an average aspect ratio ranging from 1.5 to 7. In addition, U.S. Pat. No. 4,386,156 discloses a method for preparing a tabular silver bromide emulsion having an average aspect ratio of 8 or more by ripening seed grains in the absence of non-silver halide ion complexing agents.
As described above, emulsions consisting of tabular silver bromide grains having (100) crystal faces as their major faces have been reported. To use these emulsions as silver halide photographic light-sensitive materials, however, further improvements are required in particularly photographic sensitivity.